Detection and analysis of two serotypes of ammonia-oxidizing bacteria in sewage plants by flow cytometry

Two different serotypes of the genus Nitrosomonas were isolated from samples of the sewage plant Heidelberg. These nitrifiers were enumerated in activated sludge of various other sewage plants after immunofluorescent labeling and staining with propidium iodide by flow cytometry. The concentrations of these serotypes of Nitrosomonas spp. were in the range of 0.1 to 2%. Also, a test for the determination of the activity of ammonia-oxidizing bacteria was developed. Nitrite-oxidizing bacteria were specifically inhibited with sodium chlorate, and the activity of ammonia-oxidizing bacteria could be calculated from the increase of nitrite. Concentrations and activities of ammonia oxidizers were measured for a period of 6 months in the sewage plant Heidelberg. With one exception, activities and concentrations of ammonia-oxidizing bacteria decreased and increased in parallel.     

Evaluating the stoichiometric trait distributions of cultured bacterial populations and uncultured microbial communities

We measured the stoichiometric trait distribution of cultured freshwater bacterial populations under different resource conditions and compared them to natural microbial communities sampled from three lakes. Trait distributions showed population differences among growth phases and community differences among lakes that would have been masked by only reporting the mean biomass value. The stoichiometric trait distribution of the environmental isolates changed with P availability, growth phase and genotype, with P availability having the strongest effect. The distribution of biomass ratios within each isolate growth experiment were the most constrained during the stages of rapid growth and commonly had unimodal distributions. In contrast to the population distributions, the distribution of N:P and C:P for a similar number of cells from each of the lake communities had narrower stoichiometric distributions and more commonly exhibited multiple modes. © 2019 Society for Applied Microbiology and John Wiley & Sons Ltd     

Transition state stabilization by six arginines clustered in the active site of creatine kinase

Six fully conserved arginine residues (R129, R131, R235, R291, R319, and R340) closely grouped in the nucleotide binding site of rabbit muscle creatine kinase (rmCK) were mutated; four to alanine and all six to lysine. Kinetic analyses in the direction of phosphocreatine formation showed that all four alanine mutants led to substantial losses of activity with three (R129A, R131A, and R235A) having no detectable activity. All six lysine mutants retained variable degrees of reduced enzymatic activity. Static quenching of intrinsic tryptophan fluorescence was used to measure the binding constants for MgADP and MgATP. Nucleotide binding was at most only modestly affected by mutation of the arginine residues. Thus, the cluster of arginines seem to be primarily responsible for transition state stabilization which is further supported by the observation that none of the inactive mutants demonstrated the ability to form a transition analogue complex of MgADP.nitrate.creatine as determined by fluorescence quenching assays. As a whole, the results suggest that the most important role these residues play is to properly align the substrates for stabilization of the phosphoryl transfer reaction.     

Two in a bed: The influence of couple sleeping and chronotypes on relationship and sleep. An overview

Objective: To summarize research on couple sleeping with respect to gender-specific differences and chronotype. Methods: Systematic review of the literature. Results: Millions of adults around the world share their beds with a partner. This may be an expression of intimacy and attachment and tends to intensify romantic relationships. Yet, couple sleeping still has underestimated implications for the quality of the relationship, quality of sleep and for physical and psychological health which are not consistently positive. Implications for research and therapy are discussed. Conclusions: Despite the people involved perhaps not even being aware of their nocturnal interactions, it is important that sleeping together becomes a subject of discussion.

Abbreviations: REM: rapid eye movement; QOL: quality of life; OSA: obstructive sleep apnea; CPAP: continuous positive airway pressure     

A high-throughput screening assay for the identification of flavivirus NS5 capping enzyme GTP-binding inhibitors: implications for antiviral drug development

There are no effective antivirals currently available for the treatment of flavivirus infection in humans. As such, the identification and characterization of novel drug target sites are critical to developing new classes of antiviral drugs. The flavivirus NS5 N-terminal capping enzyme (CE) is vital for the formation of the viral RNA cap structure, which directs viral polyprotein translation and stabilizes the 5' end of the viral genome. The structure of the flavivirus CE has been solved, and a detailed understanding of the CE-guanosine triphosphate (GTP) and CE-RNA cap interactions is available. Because of the essential nature of the interaction for viral replication, disrupting CE-GTP binding is an attractive approach for drug development. The authors have previously developed a robust assay for monitoring CE-GTP binding in real time. They adapted this assay for high-throughput screening and performed a pilot screen of 46 323 commercially available compounds. A number of small-molecule inhibitors capable of displacing a fluorescently labeled GTP in vitro were identified, and a second functional assay was developed to identify false positives. The results presented indicate that the flavivirus CE cap-binding site is a valuable new target site for antiviral drug discovery and should be further exploited for broad-spectrum anti-flaviviral drug development.     

Spruce photosynthesis: possibility of early damage diagnosis due to exposure to magnesium or potassium deficiency

Summary The effects of exposure to magnesium or potassium deficiency on spruce needle photosynthesis were studied before symptoms of damage were visible, and recovery was followed. Water content, pigment content and O₂ evolution rate were chosen as parameters of physiological activity in addition to chlorophyll fluorescence. In the case of exposure to Mg deficiency, the first symptoms detected by all the physiological parameters were observed in older needles. An effect on chlorophyll fluorescence [decrease in fluorescence index (R_fd) and photochemical quenching (q_Q), and increase in non-photochemical quenching (q_E)] was detected in younger needles at the beginning of the deficiency treatment with little effect on the other physiological parameters [decrease in water content to 96.5%, and in photosynthetic rate expressed over dry weight (PSDW) to 90.7%]. No recovery was observed. After a K-deficiency exposure, both kinds of needles were affected, but a high recovery rate was observed, especially in the current-year needles, where a complete recovery from damage was detected by fluorescence and confirmed later by visual inspection. Finally, these results indicate the possibility of an important early diagnosis of damage in forest decline and suggest that chlorophyll fluorescence can be used, at least in the laboratory, as a qualitative test of plant health.